1) Field of the Invention
This invention is concerned with an improvement in the distributive ejection device for liquid material to be used in freeze-drying apparatus for foodstuffs, medicaments, and so on, the liquid material being prepared from those foodstuffs, medicaments and so on in their desiccated conditions; such liquid material being distributively ejected into the inner cavity of an upright cylindrical tube, followed by its freezing on the inner wall surface of the cylindrical tube; then sublimating the moisture (or water) content in the material by application of sublimation heat under the vacuum condition to obtain the freeze-dried product.
2) Description of Prior Arts
Conventional freeze-drying apparatus, in which the materials to be freeze-dried such as foodstuffs, medicaments, etc. are adjusted into a liquid form and kept frozen, after which it is desiccated by application of sublimation heat to the materials for desiccation, under the vacuum condition, to sublimate the moisture content in the material, has usually been done in such a manner that the materials to be desiccated are adjusted into a liquid form, then the liquid material is filled in a desiccating vessel such as trays, etc., each desiccating vessel being placed in a desiccating chamber of the freeze-drying apparatus provided with storing shelves, wherein these desiccating vessels are subjected to freezing to sublimate the water content in the liquid material by supplying the sublimation heat, within the drying chamber, to capture the water vapor from the liquid material as frozen by means of a vacuum exhaustion type cold-trap which is communicatively connected to the desiccating chamber.
As another expedient, there is one which has been developed by the applicants of the present invention. This expedient is of such a construction that, as shown in FIG. 1 of the accompanying drawing, the desiccating chamber of the freeze-drying apparatus is formed of a multitude of upright cylindrical tubes 1, 1, . . . to cause the liquid material to freeze on the inner wall surface thereof, which are arranged side by side in bundle at a predetermined space interval; then, a jacket 2 for circulating heat medium in and through each of these upright tubes is shaped in a bucket- or vessel-form and mounted on and around each of these bundled tubes; thereafter, an inlet tube 20 and an outlet tube 21 of this bucket- or vessel-shaped jacket 2 are connected to the tube-passageway of a heat-exchanger (not shown in the drawing) for heat-exchanging of the heat medium, thereby causing the heat medium to circulate within the jacket 2, while, at the upper end side of each of the multitude of thus arranged tubes 1, 1, . . . , there are communicatively connected a duct 3 of a vacuum exhaust system, equipped with a vacuum pump or a cold-trap 30; and, at the lower end side of each of the tubes 1, 1, . . . , there are provided an opening-and-closing valve V to hermetically close the tubes, and a recovery chamber 4 below the valve V by connecting the same to the lower surface side of the jacket 2. Within the duct 3 which communicates with the upper end side of each of the tubes 1, 1, . . . , there is disposed a distributive ejection head 7 connected to the downstream side of the abovementioned tube passageway 5, to which distributive ejection nozzles 70, 70, . . . corresponding to each of the tubes 1, 1, . . . , are provided. With these distributive ejection nozzles 70, 70, . . . , the liquid material is distributively fed into the inner cavity of each of the tubes 1, 1, . . . , thereby freezing the liquid material onto the inner wall surface 1a of each of the tubes 1, 1, . . . , which has been kept cooled by the heat medium within the jacket 2. As soon as the frozen layer reaches a predetermined thickness, the liquid material, which is flowing down in its unfrozen state, is drawn outside through a take-out tube 6 disposed on one part of the upper surface side of the valve V and at the lower end side of the tubes 1, 1, . . . , whereby the liquid material is frozen in the columnar shape having a predetermined thickness on the inner wall surface of each of the tubes 1, 1, . . . This frozen columnar material on the inner wall surface of the tubes is maintained under the vacuum condition by means of a vacuum exhaust system, which is communicated with the duct 3, to cause the water content to be sublimated from this frozen liquid material for its freeze-drying. As soon as the frozen material is completely desiccated, the valve V is opened and the dried product of the liquid material, as desiccated in its columnar shape, is dropped into the recovery chamber 4 as the desiccated bulk, and is taken outside.
The conventional means for adjusting the abovementioned material for foodstuffs, medicaments, and so forth into liquid form, and then freeze-drying the thus adjusted liquid material necessitates installation of a facility for prevention of contamination, careful operations of the facility, and care-taking in its maintenance, in one means of a type, wherein the liquid material is distributively fed into vessels (or containers), then the liquid material together with the container is placed in a desiccating chamber of the freeze-drying apparatus, and subjecting the material to freeze-drying under the vacuum condition, in the course of distributively feeding the liquid material as adjusted into the vessels, and of placing these vessels filled therein with the liquid material into the desiccating chamber of the freeze-drying apparatus, the working and operations of which are complicated and troublesome, hence problems exist in many aspects such as guarantee of sterilization in the facility, prevention of the facility from risk of contamination, and others.
In the other means of a type, wherein the freeze-drying of the liquid material is carried out by use of the freeze-drying apparatus, in which the desiccating chamber is constructed with upright cylindrical tubes, the liquid material to be frozen onto the inner wall surface of the tubes by distributive feeding of the liquid material into the upright cylindrical tubes is subjected to desiccation at a uniform rate by vacuum sublimation, between the upper end side of the tube and its lower end side, on account of which the liquid material needs to be frozen onto the inner wall surface of the tube in the shape, wherein the axial part thereof takes a hollow cylindrical shape. On account of this, the liquid material should be distributively fed to the inner wall surface of the tube so as to attain substantially uniform thickness over its entire surface, which gives rise to difficult problems.
Also, if and when the liquid material is fed by ejection against the inner wall surface of the tube 1, through the distributive ejection nozzles, and, if and when the outer peripheral surface thereof comes into contact with the inner wall surface 1a of the tube 1 which has been kept cooled by the heat medium within the jacket 2, the liquid material is instantaneously frozen, and, since the liquid material which is ejected consecutively becomes frozen sequentially over the frozen layer of the liquid material which has been kept frozen, if and when there exists irregular distribution of the liquid material at the time of its ejection from the distributive ejection nozzle 50, the irregularity in the liquid material as ejected is amplified with increase in the layer thickness of the frozen layer, which sequentially develops into a thick laminated layer to inevitably become an irregular frozen layer to cause serious problem.
The present invention has been made with a view to solving the problems inherent in the conventional means, and to providing improved means for carrying out freezing of the liquid material onto the inner wall surface of the tube, which material was adjusted from the starting materials for foodstuffs, medicaments, etc., using a freeze-drying apparatus of a type, wherein the desiccating chamber is constructed with upright cylindrical tubes, and then the moisture content in the material is sublimated under the vacuum to be freeze-dried, when the distributive ejection of the liquid material to the tube is made in such a manner that the liquid material is fed onto the overall surface of the inner wall surface of the tube to a substantially uniform thickness.
As the means for attaining the abovementioned objective, the present invention provides means of a construction, as illustrated in FIG. 2 of the accompanying drawing, in which a cylindrical wall a, projecting upwardly of a jacket 2 for circulation of heat medium, which is disposed on the outer periphery of the upright cylindrical tube 1, is provided on the upper end side of the tube 1 to be equipped in the freeze-drying apparatus w, in a configuration wherein the peripheral wall of the tube 1 is extended; then, the liquid material is sprayed from the distributive ejection nozzle 70, which is disposed at the downstream side of the tube passageway 5 for supplying the liquid material, to the inner wall surface of the cylindrical wall a in a state of its being rendered uniform in the circumferential direction on and along the inner wall surface of the cylindrical wall a, in which condition the liquid material flows down along the inner surface of the cylindrical wall a to secure good flowing on the inner wall surface 1a of the tube 1, which constitutes the freezing surface of the liquid material.
With this expedient, the liquid material ejected from the distributive ejection nozzle 70 is forced out against the inner surface of the cylindrical wall a, which is so provided as to be extended upward from the upper edge of the tube 1, and which assumes a state such that the outer peripheral surface of the tube does not come into contact with the heat medium within the jacket 2. At this location, the liquid material, in its unfrozen condition, is spread in the form of film, along the inner surface of the cylindrical wall a, in which state the liquid material flows down on and along the inner surface of the cylindrical wall a, and tends to flow onto the inner wall surface of the tube 1. As the consequence, the liquid material is fed to the inner wall surface 1a of the tube 1, on which the frozen layer of the liquid material is formed, in the state of its being made flat and smooth in its circumferential direction, and becomes sequentially frozen onto the inner wall surface 1a of the tube from its upper end side toward its lower end side.
At this time, since the liquid material which tends to flow onto the inner wall surface 1a of the tube 1 from its upper edge side is kept at a certain predetermined temperature, there is no possibility of the liquid material to gather at the upper end position of the inner wall surface 1a, which constitutes the inlet part, to freeze, but, owing to the liquid material being gradually cooled in the course of its flowing down on and along the inner wall surface 1a of the tube 1, such liquid material becomes gradually frozen over the entire surface of the inner wall surface 1a with a uniform thickness throughout.
However, progress in the cooling of the liquid material during its flowing down would increase the rate of freezing of the liquid material onto the inner wall surface 1a of the tube 1, whereby thickness of the frozen layer of the liquid material at the lower end side of its inner wall surface 1a tends to increase its thickness. Therefore, measures are taken to avoid such undesirable increase in thickness, such that the jacket 2 surrounding the outer periphery of the tube 1 is defined in a plurality of numbers on both up-side and down-side of the tube, and temperature of the heat medium to be circulated within the jacket 2 is controlled individually so as to become gradually higher, between a position corresponding to the upper side of the inner wall surface 1a of the tube 1 and a position corresponding to the lower side thereof.
In the next place, as an expedient which has been developed from the abovementioned means, the present invention provides means as shown in FIG. 3, wherein the cylindrical wall a, which is so provided as to be extended upward from the upper edge of the tube 1, is formed in a funnel-shaped slant wall b, with its diameter being gradually increased upward, and with the liquid material to be ejected from the distributive ejection nozzle 70 being blown against the part which is closer to the upper end side of this funnel-shaped slant wall b. In this way, the liquid material sputtered onto the inner surface of the cylindrical wall a with an inclined wall b, and made in a uniform thin film, gradually flows down to the reduced diameter part of the inclined wall b, whereby the liquid material is concentrated in the circumferential direction in the state of its being rendered uniform with increased thickness, while it flows onto the inner wall surface 1a of the tube 1.
Since this means is capable of increasing the flow-rate of the liquid material which flows onto the inner wall surface 1a of the tube 1 by being rendered uniform with the inner surface of the cylindrical wall a, it facilitates control for freezing the liquid material as the frozen layer having a substantially uniform thickness over the entire surface of the inner wall surface 1a. 
Further, as a means which has been much developed from the means, in which the abovementioned cylindrical wall a is made into a funnel-shaped slant wall b, the present invention provides means, as shown in FIG. 4, in which the cylindrical wall a is formed in a hopper-shape, wherein an upright wall c in a rectilinear cylindrical form rises from the upper edge of the inclined wall b, and the liquid material to be ejected from the distributive ejection nozzle 70 is sputtered against the inner surface of the upright wall c of this hopper-shaped cylindrical wall a. The liquid material as ejected is made into a thin film by the inner surface of this upright wall c, which is concentrated by the funnel-shaped slant wall b to flow onto the inner wall surface 1a of the tube 1.
With this means, even when the quantity of the liquid material to be ejected from the distributive ejection nozzle 70 is increased, such liquid material is made uniform by the upright wall c having a wide area, and is concentrated by the funnel-shaped slant wall b to flow into the tube 1.
Various objects of the present invention as described above will become more apparent and understandable from the following detailed explanations thereof, when read in conjunction with the specific embodiments thereof as shown in the accompanying drawing.